The invention relates to the tagging of objects in order to confirm or detect their presence in a predefined space at a predefined time. The invention further relates to straps for devices for which any attempt at tampering needs to be reported automatically and to fastening means for such straps.
The tagging of objects in order to confirm or detect their presence in a predefined space at a predefined time is desirable in certain situations. The electronic tagging of offenders is known and is being used more often. In particular, with increasing overcrowding of prisons and other offender institutions, many authorities are beginning to use electronic tagging to allow early release or house arrest of certain offenders. Electronic tagging may also be used to monitor of the presence of a person in a particular area. This may be particularly useful to monitor patients in a hospital or other institution and may also be used for people working in a secure environment such as a nuclear power plant or a military establishment.
Electronic monitoring devices may be used to monitor the presence of a person or animal, for example racehorses or pedigree dogs, or may be used to monitor the presence of an object such as laptop computers or other expensive items.
An electronic tag or monitoring device, often referred to as a personnel monitoring device when used on people, usually includes a circuit board with a radio transmitter and batteries in a housing and a flexible strap that is fastened around the writs or ankle of the person. The device may only be removed by breaking the fastening, cutting the strap or breaking open the housing. The device includes a number of tamper detection features such as a flexible printed circuit board within the strap that forms a complete circuit when the strap is fastened on the person and proximity sensors to indicate if the device is in proximity to the body of the user. A signal is sent from the radio transmitter to a monitoring unit in, for example, the person""s home. This may be connected to a normal phone line and if the person leaves the vicinity of the monitoring unit or if there is any tampering with the tagging device, the information is transmitted to a central unit or service provider and a follow-up investigation can be carried out. A tamper signal will be sent if the strap is cut and the circuit is broken or if the housing is tampered with. Proximity sensors on the flexible printed circuit board will send a tamper signal if the strap is removed from the person""s limb or if adjacent parts of the strap are separated.
The device needs to fit closely but comfortably on the user. In particular, it needs to be fastened on securely so that it cannot be removed without alerting the monitoring unit and without showing visible signs of tampering. Present types of tagging device have a strap that is fastened together by rivets or screws or similar fastening devices that need tools to fix them. Snap together closures that form a permanent lock on a strap are also known. All these types of fastenings form a permanent closure such that the strap has to be cut to remove the device from the user.
A particular disadvantage of presently used devices is the need to use tools to fasten the strap. This means that straps take some time to fit and the fitter is required to have additional equipment as well as expertise in fitting the devices. A further disadvantage of presently used devices is the lack of reusability of the device once the strap has been cut. The batteries that are commonly used in electronic tagging devices may have a usable life of about 8 months but typically these devices are used for a much shorter period on any one person. Thus, it would be advantageous to have a tagging device that could be easily used for more than one person.
It is an object of the invention to provide a tagging device having a strap with a fastening means that is simple and easy to close, that shows evidence of any tampering but that enables the strap to be reused. Further objects of the invention include providing such a strap that can easily be adjusted to fit a variety of sizes and providing a tamper-evident fastening for such a strap.
The invention provides a fastening means for a strap for a tagging device in accordance with various of the appended claims. The invention further provides a combination of a strap and a fastening means for a tagging device in accordance with various other of the appended claims. The invention further provides a tagging device in accordance with yet other of the appended claims.
The strap may be integrally moulded with the housing or may be attached by suitable means such as welding. Once the electronic circuitry is in place within the housing, the housing is advantageously sealed closed. Preferably the housing further includes battery means.
Preferably the electrical circuit means included in the strap comprises a flexible printed circuit board integrally moulded within the strap.
Preferably the latch plate contacts the electrical circuit means within the strap to close a circuit around the device with the fastening means is closed.
Preferably the engagement means on one of the collar or the latch plate comprises breakable elements that engage with receiving means in the form of slots on the other of the collar or the latch plate such that the elements snap when the collar is retracted from the latch plate.
Preferably the breakable elements comprise barbs on the inside of the collar which deform to snap over ridges in corresponding receiving slots on the latch plate. These barbs are preferably strong enough to hold the collar in position on the latch plate so that it is not inadvertently disengaged but weak enough to break if the collar is forcibly removed from the latch plate. Once the barbs are broken there is visible evidence that the user has attempted to tamper with the device, even if the collar is fitted back over the latch plate without the device being removed from the user.
The collar and latch plate of the fastening means provide a xe2x80x9csingle usexe2x80x9d, tamper-evident fastening that is visibly damaged once it is opened. However, the strap is not damaged when the fastening means is opened and the device can easily be reused by replacing just the damaged part of the fastening means, conveniently the collar. In this way, a new collar is simply slipped onto the second free end of the strap, ready for the device to be fastened onto another user.
Preferably the retaining means on the latch plate comprises a lug and the retaining means on the second free end of the strap comprises at least one corresponding hole such that the lug fits into the hole to hold the first and second free ends of the strap in a fixed relative position when the fastening means is engaged.
Advantageously the device further includes means to adjust the length of the strap to suit a wide variety of user sizes. Preferably the adjustment means comprises a plurality of holes on the second free end of the strap to correspond to the lug on the latch plate such that the lug engages with a hole at a position to provide a desired size of closed strap. When the strap is fitted on a user, the second free end of the strap is adjusted to a suitable position to give a snug fit of the device on the user and the lug on the latch plate on the first free end of the strap fits into an adjacent hole on the second free end of the strap. The collar is then moved into engagement over the latch plate and holds the strap in position.
The device can be made with straps in a plurality of sizes to suit different sizes of objects but it has been found for human users that the length adjustment means enables the number of sizes required to fit the majority of the population can be reduced, advantageously to two sizes, small and large. This has the commercial advantage of enabling all users to be provided for with the supply of only two sizes, if desired.
The latch plate further comprises a connecting protrusion and the electrical circuit means in the first end of the strap includes a switch means such that when the collar is fitted over the latch plate the connecting protrusion is moved to create a contact in the switch means and when the collar is removed from the latch plate the protrusion moves to release the contact in the switch means. The movement of the protrusion over the switch means closes the electrical circuit in the strap. Advantageously the electrical circuit means further includes proximity sensors to sense if the device is adjacent the body of a user or, additionally or alternatively, to sense whether the two ends of the strap are in proximity to one another.
The latch plate may be integrally formed with the first free end of the strap or may be a separate element. If the latch plate is a separate element, it advantageously comprises at least one lug for engagement with a corresponding hole in the first free end of the strap.
The latch plate may alternatively comprise two plates for attaching on either side of the strap. The two plates preferably comprise a top plate and an actuator plate. Advantageously the actuator plate is inserted through the strap at the required position. The actuator plate and the top plate preferably comprise corresponding mating means and the top plate is positioned on the actuator plate such that the mating means engage and hold the two plates together through the strap. Advantageously the actuator plate comprises a switch actuator pin which passes through the strap to create a contact with the switch means when the collar is positioned over the assembled top plate and actuator plate.
If the tagging device is removed from the user, a remote monitoring device may be activated to provide an alert signal. Advantageously the latch plate is arranged such that moving the collar causes the contact to be broken and the alarm to be activated, even if the user attempts to hold the latch plate in position on the strap.
The device monitors its own state and determines whether there has been an attempt at tampering. If an attempt at tampering is detected, the device can communicate that to a central site, for example via a telephone link or radio signal. Preferably the electronic circuitry within the housing includes means for transmitting a signal to a location remote from the device.